Add additional bounds checks to NNAPI FMQ deserialize utility functions

This CL adds the following additional bounds checks:
* Adds additional checks of the index of the std::vector before
  accessing the element at the index
* Changes the array index operator [] to the checked std::vector::at
  method

Bug: 256589724
Test: mma
Merged-In: I3461c9e33b64e7d44bb3b430c8eb00d794669037
Change-Id: I3461c9e33b64e7d44bb3b430c8eb00d794669037